1. Field of the Invention
The present invention generally relates to image forming apparatuses and print control methods for printing data stored in an external storage device. The invention also relates to computer-readable recording media in which a print control program is recorded.
2. Description of the Related Art
While conventionally data is often printed on an image forming apparatus via a personal computer (PC), the data storage capacity of external storage devices has greatly increased in recent years. Improvements have also been made in technologies for realizing enhanced portability (i.e., smaller size). As a result, there is an increasing demand to connect an external storage device to the image forming apparatus so that data stored in the external storage device can be directly printed by the image forming apparatus.
For example, there is a printing apparatus with a predetermined slot into which a Universal Serial Bus (USB) memory with stored image data or the like can be inserted. In the image forming apparatus, the data from the USB memory can be printed via an external storage device interface (I/F).
Against this technical background, users demand increasingly greater size of data to be printed. However, memory capacity differs depending on the type of image forming apparatus, with the smaller and less expensive types having smaller memory capacity.
One of the problems of the related art is that a lack of memory (“memory overflow”) may occur depending on the kind of data to be printed, whereby the functions of an image forming apparatus cannot be fully exploited. In an image forming apparatus, during an image forming operation, image data (intermediate data) that can be interpreted by a printer engine (hereafter referred to as an “engine”) is generated from print data. The image data thus generated is retained in a memory. If sufficient free space (available memory area) to retain the generated image data is not available in the memory, a print failure may be caused.
Japanese Laid-Open Patent Application No. 2006-159702 (Patent Document 1) discloses an image processing apparatus in which a print buffer is monitored. Upon detection of a buffer-full status, an image forming method is selected that requires less image data to be written in the buffer.
However, in this technology according to Patent Document 1, whether there is a lack of memory or not cannot be determined until, for example, all of the print data transmitted from a PC is received by the image processing apparatus and image data that can be interpreted by the engine is generated from the received data and then written in the buffer area that is available in the provided memory at the time of printing.
Thus, in the conventional technology, a potential print failure is determined in the course of a normal image forming operation involving the reception of data from a PC, generation of proper image data, writing in the buffer area, and the like. Consequently, upon detection of a fault due to lack of memory, the time spent for the preceding image forming operation is wasted. In addition, in order to grasp the overall picture of the print data to verify the development of print failure, the entire data needs to be received by the image processing apparatus, so that it takes a long time when the size of the received data is large.